public class Fish {
    int weight;
}
class Lake{
    Fish fish;
    void setFish(Fish f){
        fish=f;
    }
    void eat(int n){
        fish.weight= fish.weight+n;
    }
}
class Fishlake{
    public static void main(String[] args){
        Fish Liyu=new Fish();
        System.out.println(Liyu.weight);
        Lake Xihu=new Lake();
        Xihu.setFish(Liyu);
        Xihu.eat(10);
        System.out.println(Liyu.weight);
        System.out.println(Xihu.fish.weight);
        Xihu.eat(15);
        System.out.println(Liyu.weight);
        System.out.println(Xihu.fish.weight);
    }
}